In the cornering of the motorcycle on urban areas, when a certain camber angle is given to the tire, it is generally and widely conducted to contact a tread contacting face with ground under a condition that a position of surface width measured from an equatorial plane of the tire is limited to about 50–75% of a tread half-width.
Therefore, the pneumatic radial tire for the motorcycle exclusively used in the running on urban areas is possible to sufficiently develop the desired performances by giving a large camber angle without deeply pursuing optimization on various bending rigidities of a belt, a rigidity balance and the like, which highly exerts on the steering stability in the high-speed cornering while contacting the tread contacting face with ground up to a side edge position.
In recent years, however, the motorcycle is made to higher performances, and also special control areas for sporty running such as training field, circuit and the like, at where amateur riders can enjoy drastic sporty running while challenging to a limit of the steering technique, other than public roads are increasing. As the sporty running is readily enjoyed, the cornering at a high speed while largely inclining a vehicle body, or so-called large camber running is frequently conducted. In the tires based on the conventional belt design technique and the like, therefore, it is increasing to be a dissatisfaction that the steering stability in the high-speed cornering is lacking in such a large camber running.
The invention is to solve the above problems inherent to the conventional pneumatic motorcycle tire and to provide a pneumatic radial tire for a motorcycle capable of sufficiently developing various performances such as high-speed durability, straight-running stability and the like but also developing an excellent steering stability in the aforementioned large camber running.